XX-year-old是“XX岁的”的意思,是形容词,一般用作定语,修饰名词,也可以用作名词.
XX years old,是个形容词短语,可做谓语,不可以做冠词,即不可以用来修饰名词代词等.能举个例子吗？不好意思，上面弄反了，year-old 是一个形容词词组，不可以用作名词。例子：year-old用作定语：My younger sister is a five-year-old girl. 此处five-year-old作定语修饰girl。years old 可用作谓语，后面不可修饰名词、代词。例如：He is nine years old.